4 to 6 colours sometimes more, plan the ones you put out so they mix to another colour other than brown, eg reds, yellows orange pink (No greens or blues)
blues greens yellows (no reds or orange)
pastel colours often out this time of year, (or when we top up pots using white!)
Black occasionally

Have done a week of just blue paint had about 10 different shades !

Our easel broke and children actually prefer the table so have decided to do without for a while and see how it goes.